A wide range of situations arise, which involve fixing a member such as a rotational member on for example a shaft in a piece of machinery. Typical examples of such a situation are those which involve fixing belt pulleys, gears and the like on a member such as a shaft having a cylindrical outside surface. For that purpose, it is possible to use clamping discs of a generally star-like shape, which are in the form of rings of hardened special spring steel, the rings being of a shallow conical configuration. The clamping discs of that kind are fitted into a bore or a recess in the rotational member to be secured on the shaft, the bore or recess having a cylindrical inside surface. By pressing the clamping disc towards the flattened condition, the outside diameter of the ring is enlarged and the inside diameter is reduced. As a result, the outside periphery of the ring is caused to bear against the cylindrical inside surface of the bore or recess and the inside periphery is caused to bear against the cylindrical outside surface of the shaft, thereby providing a suitable frictional locking effect as between the rotational member, the disc and the shaft. Those clamping discs are formed by radial slots in the spring steel material of the disc, the slots extending alternately from the outside peripheral edge and the inside peripheral edge thereof.
By virtue of the radial slots which impart the star-like configuration to those clamping discs extending from the inside peripheral edge and the outside peripheral edge respectively, the engagement surface areas for co-operating with the rotational member and for example the shaft respectively, and in particular the outside peripheral engagement area which co-operates with the cylindrical inside surface of the bore or recess in the rotational member, are relatively small. In addition, to produce the radial clamping effect, the clamping disc which, as mentioned, is of a shallow conical configuration, has to be pressed substantially flat, with an axially directed force being applied directly to the clamping disc.